This study evaluated whether there were increasing admissions for illicit drug abuse treatment among older persons from 1992 to 2005 in the United States and describes the characteristics, number, and type of substances most commonly abused in this population over this 14-year period. Analyses used public data files from the Treatment Episode Data Set, which tracks federally and state funded substance abuse treatment admissions. From 1992 to 2005, admissions for illicit drug abuse increased significantly; in 2005, 61% of admissions age 50 to 54 years old and 45% of admissions age 55 years and older reported some type of illicit drug abuse, most commonly heroin or cocaine abuse. Criminal justice referrals for drug abuse admissions have increased over time and daily substance use remains high. Efforts to determine best practices for prevention, identification, and treatment of illicit drug abuse in older persons are indicated.